1. Field of the Invention
The present invention relates generally to medical devices and methods for their preparation. More particularly, the present invention relates to luminal prostheses having polymer coatings and methods for their preparation.
Luminal prostheses are used for maintaining patency in various body lumens, most notably in the vasculature and the ureter. The most common form of luminal prosthesis is referred to as a “stent,” which is a generally tubular-shaped scaffold which is deployed to hold open or reinforce a segment of a body lumen. Stents are most commonly used in the vasculature where they are deployed in the coronary arteries, the carotid artery, the femoral artery, as well as in the peripheral arterial and venous vasculature. Stents and other luminal prostheses, however, also find use for treating aortic aneurysms, thoracic aneurysms, for supporting bioprosthetic valves, and for other purposes.
Stents are typically delivered to a target region within a body lumen using a catheter. Balloon-expandable stents are commonly mounted on a balloon catheter, navigated to the target region, and expanded by inflating the balloon. Self-expanding stents are most often delivered to a target region while constrained in a sheath or other tubular member. Once they reach the target region, the constraint can be removed and the stent will expand and deploy within the body lumen.
Stents and other luminal prostheses may also be modified to carry and elute drugs and pharmaceutical agents within a body lumen for a variety of purposes. Within the vasculature, the drugs and pharmaceutical agents are typically intended to reduce tissue inflammation, restenosis, or thrombosis, and/or to promote healing and biocompatibility of the device. Of particular interest to the present invention, drugs and other pharmaceutical agents are often eluted from a polymer matrix which has been coated over at least a portion of the stent surface. To be effective, the polymer should be able to accommodate stent preparation and processing as well as subsequent expansion within the vasculature or other body lumen. In particular, the coatings should suffer minimal or no cracking or smearing which can result from deformation and strain as the stent is crimped, expanded, or otherwise deformed during processing of delivery.
For these reasons, it would be desirable to provide improved coated prostheses, catheters for delivering such coated prostheses, and methods for fabricating such coated prostheses. In particular, the coatings on the prostheses should resist cracking and smearing during fabrication, preparation, and delivery to a targeted body lumen. The delivery catheters should further help reduce cracking and smearing during delivery. Finally, the fabrication methods should apply the coatings to the prostheses in a manner which promotes coatings which resist cracking and smearing. At least some of these objectives will be met by the inventions described below.
2. Description of the Background Art
The following U.S. patents and printed publications describe luminal prostheses and other implantable devices having polymer and other coatings for drug delivery and other purposes: U.S. Pat. Nos. 7,232,573; 7,163,555; 7,055,237; 7,008,979; 6,984,393; 6,918,929; 6,855,770; 6,824,559; 6,712,846; 6,653,426; 6,592,895; 6,653,426; 6,224,894; 6,153,252; and 6,120,847; and U.S. Publication Nos. 2007/0207184; 2007/0185569; 2007/0168012; 2007/0123973; 2007/0106371; 2007/0073016; 2007/0003592; 2006/0282166; 2006/0257355; 2006/0212106; 2006/0198868; 2006/0093771; 2006/0067908; and 2005/0271700.